It's been a very long wait, but the release is finally here: Adobe has released Flash Player 10.1. Since Flash has come under increasing scrutiny, there's a lot at stake here for Adobe. This release is supposed to use far less resources while still being faster, more stable, and more secure. Update:No 64bit Flash player for now - on any platform. The Linux beta has been axed.

..your developers having trouble compiling against the 64bit libraries? Maybe you need to look to your source code and figure out why it's such a mess.

I doubt it.
Most likely the original developers randomly scattered int/long/DWORD/etc without thinking that one day the may have different meaning under once you 64bit.
Another option is poorly written assembly code that cannot be easily ported to 64bit.

In order to developer a cross-arch / cross-platform code that can easily be ported from one environment to another one needs to design the system as such from day one. Most likely Adobe only targeted a single 32bit platform and developed the code accordingly.